Although we have demonstrated the specific binding site for tocopherol in the isolated adrenal cell membrane, the nature of the binding has not been fully elucidated. We are, therefore, planning to concentrate on this aspect of research by 1) establishing more precisely the specificity of the tocopherol binding site by studying the kinetics of labeled tocopherol in the presence and absence of numerous analogues of tocopherol as well as other fat-soluble vitamins; 2) establishing the kinetics of binding in the presence of other fators which stimulate or inhibit steroidogenesis, such as prostaglandin, ACTH, ACTH analogues, ascorbate, or other anti-oxidants; 3) investigating the number of binding sites for tocopherol on the intact isolated adrenal cells and establishing the relationship of these binding sites to that of labeled ACTH; 4) solubilizing membrane proteins and establishing more clearly if the binding of the tocopherol has a specific affinity for any of the solubilized proteins on the membrane; once this has been elucidated, the relationship of the tocpherol-binding proteins to ACTH affinity will be pursued; 5) studying the concept of down regulation or up regulation in regard to vitamin E-sufficient or -deficient state on the adrenal cell membrane. Whether in fact such a phenomenon exists for tocopherol-membrane interaction is not clear. If the concept of down regulation, which is operative for hormones is valid for tocopherol, one should then be able to note an increased number of receptor sites for tocopherol in the vitamin E-deficient state. Similarly, a decreased number of receptor sites in the vitamin E-sufficient state should be evident.